For consumer applications staples are used in both staple guns and desktop staplers. Both may be referred to as staplers. Staple guns usually employ a heavier staple and stapling mechanism than desktop staplers, and do not include a separate base and anvil element. However desktop staplers may also be of a heavy-duty format if intended for large stacks of paper. Standard light duty staplers typically fasten a maximum of 20 sheets of paper.
The staples are provided in a rack that includes a line of staples glued together edge-to-edge. The strength of the glue must be sufficient to hold the rack together during handling and use of the staples. The staples are held in or on a track; a front most staple extends past the track to a position under a striker. The striker shears off the front staple so that the staple can be ejected out if the stapler. The glue that holds the rack together must not be too strong or it will require excessive force to separate the front staple by shearing. The consistency of the glue that holds the staples in the rack is an important part of manufacturing staples.
In a direct action stapler, where a handle is directly linked to the striker, a user must directly overcome the staple rack glue shear force needed to separate the front staple. Direct action is typical in desktop staplers. The shear force can be a large part of the apparent effort of such stapling. In a spring-actuated stapler the impact action makes the user unaware of the shearing step of ejecting a staple. The fast moving spring is plenty strong enough to overcome the shear strength of the glue. In any spring actuated stapler the energy of the striker after it released is far more than required for shearing a normal staple.
Co-pending U.S. patent application Ser. No. 10/443,854 shows a light duty spring actuated desktop stapler. The disclosure is incorporated herein in its entirety by reference. In a light duty spring actuated desktop stapler the spring may not be strong enough to shear the staple if the handle is not pressed far enough to release the striker. In this case the striker has no momentum, but rather presses the staple with just the static force generated from deflection of the spring. The design of the above referenced application is very efficient. This of course is desirable to make an easy to operate stapler. However it means that the static force of the deflected spring will be particularly low since a less stiff spring is needed in the efficient design. If the spring cannot shear the front staple with static force, then the striker will remain atop the front staple with the spring energized. In this condition the device may be non-functional until the staple is ejected. Further the staple may eject unexpectedly.
It is desirable to reduce the force required to shear the front staple from a rack.